Someday, perhaps as early as this fall, USC fans will look back at the Pete Carroll Era and … sigh.

Let’s think about this: For most of a decade, USC fans didn’t just hope for a national-championship contender, they expected it.  And they got it.

Seven consecutive BCS bowl teams. Seven consecutive No. 4-or-better national rankings. Seven consecutive Pac-10 titles. The 34-game winning streak. Those two national titles in the middle of the decade, and coming within a desperate, fourth-down, last-minute Vince Young scramble from a three-peat.

And a program stunned, shocked to utterly collapse last season and finish … 9-4. With another bowl victory.

Know what? Pete Carroll may look back at this someday, too … like, say, September,  when he examines his Seattle Seahawks roster and realizes he had almost as much talent at Troy … and sigh, too.

But when we deconstruct this, on that day when we look back, we may come to the conclusion that it was time for Pete to go — even if we could foresee trouble for everyone involved.

USC and Pete Carroll were almost a perfect marriage. A football school with great history and ridiculous expectations and a coach who embraced it all — and took it to a level not even the Trojans had ever known.

Howard Jones got the program rolling. John McKay was special. John Robinson had some nice years. But none of them had seven years like Pete did from 2002-2008, when the Trojans went 82-9.

Carroll was like a jolt of adrenaline into the heart of the program almost from Day 1. Running around the practice field like a kid. Looking fresh and vigorous, even though he turned 50 in the first weeks of his first season. (He is 58, now.)

Carroll is charismatic. No question. How else to explain how he recruited as well (or better) than anyone in the country for nearly a decade? Fans want to be around him. Journalists find him fascinating. Recruits flock to him. The mop of gray-white hair. The crooked nose. The trim profile. The infectious grin. He is appealing. No question.

So, where does the Trojans find another guy just like that … one who offers such an appealing face to the program and goes  82-9 in seven years,  97-19 in nine? With three Heisman Trophy winners?

The answer is … they don’t. USC has been playing football for more than a century, and caring about it passionately for most of that time, and they finally struck gold with Pete Carroll.

Any coach with a brain in his head actually does not want to be USC’s next coach,  because where does he go, after Pete Carroll?

Down, is the answer. Down.

What you really want to be is the guy who coaches USC after the guy who is after Pete. When a season or two of 6-6 makes 9-4 look appealing again.

But USC losing Pete Carroll … there isn’t anyone to blame. Because even though I don’t see this being a felicitous development for USC or Pete Carroll, this was the time for him to go.

USC just had a season in which it seemed as if half the league had caught up to USC. Carroll, considered a defensive whiz, ran out a defense that gave up scads of points.

Meanwhile, the steady rot on the offensive side of the ball continued. It really hasn’t been the same since Norm Chow left, after the 55-19 nuking of Oklahoma in the BCS title game. And it certainly hasn’t been the same since Matt Leinart and Reggie Bush left, followed by two years of John David Booty-ish blandness, one year of Mark Sanchez and a random season of the freshman, Matt Barkley.

Those once-a-year defeats in the Pac-10 suddenly turned into two-a-year … and then four-a-year.

Carroll seemed to be losing his edge. He still got the recruits he wanted, but they either weren’t as good as he thought or his constantly changing staff wasn’t coaching them up as they once had. The swagger was there, but it seemed more a learned behavior than a true belief.

Some other cracks began to show. Sanchez leaving a year before Pete planned for him to go was part of it. Underclassmen now are heading for the NFL like rats off a sinking ship.

Then there is the matter of the Reggie Bush investigation, which is still out there, somewhere … and the Joe McKnight thing, which is just picking up steam. Sanctions could be coming down, and maybe Carroll knows something we don’t.

That whole idea of “Winning Forever,” which was supposed to be the name of a book to come out this winter (have to assume that ain’t happenin’, now), seemed to be a joke.

So, with the talent down, questions about his coaching and hiring acumen being raised, the aura of USC invincibility punctured, the NCAA still snooping and even a story or two about his personal life (see: Charlie Weis) … USC suddenly didn’t seem quite as attractive.

Just as the Seattle Seahawks came along.

Having been in a room with Pete Carroll lots and lots of times (before Hong Kong and Abu Dhabi), I can assure you that you could almost see him bristle whenever anyone brought up the NFL, and the suggestion that he might somehow not have been a complete success there.

But the facts say he was not a success. In four seasons as an NFL head coach, Carroll was 33-31, and 1-2 in the playoffs. That is, he is 34-33 in his NFL career, which is as close as you can get to a non-winning record without actually being there.

Also, now, it is fair to ask if Pete Carroll can win in a situation where he will not have demonstrably better talent than the opposition, as was the case at USC, where he some years had blue-chip linebackers and tailbacks stacked up like cord wood. Where he will not be able to walk into a player’s home and convince him to come play for Pete Carroll.

Then NFL is bad about that. It insists on parceling out talent equally, and only a handful of elite coaches manage to go even 11-5 with any kind of regularity.

So far, Pete Carroll has four seasons of NFL non-greatness. But now he’s going to be smarter than he was a decade ago? More contemporary? More up to speed on NFL trends? Younger and more energetic? He will make more money, and he may have more input into roster moves than most guys in the league. But it probably won’t matter.

Maybe he can get some traction in the laughably weak NFC West. But the Seahawks and Pete as contenders for a championship? Not likely. Really not likely.

So, a year from now … USC likely will have gone something like 7-6 without Pete. The Seahawks will go around 8-8 with him. No one will be happy.

But Carroll will have that $35 million over five years, and that will keep him warm as he enters his 60s. And, really, was staying at USC really an option? For all the reasons we outlined above?

An end of an era. You bet. USC will not be this successful again for a very, very long time. And Pete Carroll will never be this successful again. At all. Anywhere.

It’s sad to see this dynamic duo, Pete and Troy, broken up. It was a hell of a ride. But most of us could see the ride was over, and everyone was heading for the exits.

It will be interesting to see how it all goes down, in the fall of 2010.  Not well, is our guess.